"This was a tough call, and reasonable people can disagree with my conclusion that these individuals should be tried in federal court rather than a military commission," Holder told the Senate Judiciary Committee. "I am confident this decision ... will withstand the judgment of history."
Holder announced last week he intended to try Khalid Sheik Mohammed and four other detainees being held at the military prison at Guantanamo Bay, Cuba, in federal court in New York instead of before a military commission. He also announced that a military commission was the proper venue for other detainees, including the alleged bomber of the USS Cole.
Holder said he wanted to clear up some misconceptions about the civilian prosecutions.
"We know that we can prosecute terrorists in our federal courts safely and securely because we have been doing it for years," he said. "There are more than 300 convicted international and domestic terrorists currently in Bureau of Prisons custody, including those responsible for the 1993 World Trade Center bombing and the attacks on our embassies in Africa."
He said classified material would be protected during the trial through the Classified Information Procedures Act, which has been used "to protect classified information in a range of terrorism cases."
Whoever presides over the trial would not give Mohammed "a platform to spew his hateful ideology," Holder said.
Finally, "I expect to direct prosecutors to seek the ultimate and most uncommon penalty for these heinous crimes," Holder said. "And I expect that they will be held in custody under Special Administrative Measures reserved for the most dangerous criminals."
Senate Judiciary Chairman Patrick Leahy, D-Vt., expressed confidence in Holder and the U.S. judiciary system in handling the trial.
"New York was one of the primary targets of the September 11 attacks," Leahy said. "Those who perpetuated the attack should be tried there. They should answer for their brutality and for the murder of thousands of innocent Americans."